An assembly of this kind involves a piston with a cooling channel, i.e., the cooling of the piston is accomplished by the spraying of cooling oil from the end near the piston skirt in the direction of the at least one feed opening for cooling oil in the cooling channel. The cooling oil penetrates into the cooling channel and accomplishes here in a manner known per sea cooling of the piston especially in the region of the piston head.
Due to the high thermal stress of modern pistons, it is desirable to also cool the undersurface of the piston crown, the so-called “dome”. For this, DE 10 2006 056 011 A1 proposes providing three spray nozzles for cooling oil, two of which are meant to serve for the supplying of the cooling channel with cooling oil and the third for the cooling of the undersurface of the piston crown. The cooling oil jet for the cooling of the undersurface of the piston crown is, however, widely spread out, so that its cooling action is inadequate, especially since the path of the cooling oil jet from the connecting rod or structures inside the piston is at least partly blocked.
To solve this problem, the German patent application 10 2013 013 962.7 proposes having only one oil spray nozzle as well as a jet divider inside the piston, which deflects a portion of the cooling oil jet ejected by the oil spray nozzle specifically onto the undersurface of the piston crown. However, the cooling action is not optimal, since due to the dividing of the cooling oil jet both for the cooling channel and also for the undersurface of the piston crown a smaller cooling oil quantity is available.